a mind like a sieve

a mind like a sieve

The tendency to be exceptionally forgetful or absentminded; a poor memory. I need to start getting more sleep at night, because lately I've had a mind like a sieve. John has a mind like a sieve—I had to leave him three separate reminders about the play tomorrow night!
See also: like, mind, sieve
Farlex Dictionary of Idioms.

a mind like a sieve

or

a brain like a sieve

If you have a mind like a sieve or a brain like a sieve, you have a bad memory and often forget things. He's lost his keys again — he's got a mind like a sieve, that boy.
See also: like, mind, sieve
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • sieve
  • have a memory like a sieve
  • have a mind/memory like a sieve
  • have a mind like a sieve
  • scatterbrain
  • a whale of a
  • shoot the lights out
  • minded
  • absent-minded
  • blond moment